Visual examination apparatus

ABSTRACT

An automated visual examination apparatus for measuring visual sensitivity and mapping blind spot location including a projection system for displaying to a patient a series of visual stimuli, a response switch enabling him to indicate his reaction to the stimuli, and a recording system responsive to both the visual stimuli per se and the patient&#39;&#39;s responses, the recording system thereby providing a correlated permanent record of both stimuli and response from which a substantive and readily apparent visual evaluation can be made.

United States Patent Haines et al.

[54] VISUAL EXAMINATION APPARATUS [75] inventors: Richard F. l-laines,Palo Alto; James W. Fitzgerald, Atascadero; Salvadore A. Rositano, SanJose, all of Calif.

[73] Assignee: The United States of America as represented by-theAdministrator of the National Aeronautics and Space Administration,Washington, DC.

22 Filed: July 6,1971

[21] Appl. No.: 159,857

[52] US. Cl ..35l/23, 128/21 R, 351/30,

[51] Int. Cl. ..A6lb 3/02, A6lb 3/06, A61 b 5/00 [58] Field of Search..351/23, 24, 30, 36;

l28/2.l B, 2.1 R

[56] References Cited UNITED STATES PATENTS 2,564,794 8/1951 Shekels..35l/23 X CONDITIONER CONTROL UNIT X-Y RECORDER June 5, 1973 3,172,4043/1965 Copenhaver et al .135 1/24 X 3,421,498 1/1969 Gans ...35l/24 x3,476,465 11/1969 Jackson et al.. ..35l/23 3,317,268 5/1967 Oswald..35l/30 Primary Examiner-Ronald L. Wibert Assistant ExaminerPaul A.Sacher Attorney-Armand G. Morin, Sr., Darrell G. Brekke and John R.Manning [57] ABSTRACT An automated visual examination apparatus formeasuring visual sensitivity and mapping blind spot location including aprojection system for displaying to a patient a series of visualstimuli, a response switch enabling him to indicate his reaction to thestimuli, and a recording system responsive to both the visual stimuliper se and the patients responses, the recording system therebyproviding a correlated permanent record of both stimuli and responsefrom which a substantive and readily apparent visual evaluation can bemade.

5 Claims, 9 Drawing Figures PAIENIEUJUII 5 I973 3.737.217

SHEET 1 OF 4 SIGNAL CONDITIONER FILMSTRIP CONTROL UNIT Fig.1 /8

X-Y RECORDER 64 r F /g-2 CRT CRT CONTROL ELECTRONICS INVENTORS TESTRICHARD F. HAINES Fig 3 PROGRAM JAMES w. FITZGERALD SOURCE BY SALVADOREA. ROSITANO ATTORNEY PAIENTEDJUH 5 Im- SHEET 3 BF 4 0 VISUALSENSITIVITY- RMAL RIGHT EYE 8 LA m n T m MW N v E Wm T T DW O m w H ML mJA y SA PAIENTEDJUH 5 I973 3. 737.21 7

APPING- INVENTORS I YE RICHARD F. HAINES ES w. FITZGERA JAM F i g 8 BYSALVADORE A.ROSI o WJWM a ATTORNEY VISUAL EXAMINATION APPARATUS Theinvention described herein was made by employees of the United StatesGovernment and may be manufactured and used by or for the Government forgovernmental purposes without the payment of any royalties thereon ortherefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates generally to visual examination apparatus and, moreparticularly, to an automated visual sensitivity tester for examiningthe eyes of a human being to determine visual field sensitivity andblind spot size, shape, and position.

2. Description of the Prior Art Because of the rather substantialdependence of an astronaut on his visual perception and the high degreeof likelihood that such perception might change without notice duringlong term space flight, it is important that vision testing means beprovided for enabling him to periodically test and evaluate his visualcapabilities.

A test of visual sensitivity during long durations of space flight isimportant because of the possibility of the occurrence of changes in thetransparency of the eyes optic media due to the impingement of variousionizing radiations, foreign matter, or cataract development; changes inthe neural, biochemical and/or photochemical processes which underlievisual sensitivity; and changes in the visual perception due to a widerange of retinal and central nervous system dysfunctions which effectsensitivity. In addition, mapping the size, shape, and location of theblind spot is of value not only in determining the state of retinal(thus visual) function near the perimeter of the blind spot, but inproviding an indication of changes in intraocular pressure. It iswell-known that an intraocular pressure change may indicate such thingsas the presence of ocular inflammmation, changes in blood pressure,elasticity of retinal vessels, body temperature, alkalinity, and osmoticpressure of the cardiovascular system, closure or clogging of theanterior ocular chamber, or variation of the volume of any of theintraocular areas.

Presently, no fully automated visual field testing or blind spot mappingapparatus is commercially available. Although there are available ofnumber of handoperated visual perimeters, such as the Goldmann Perimeterand the Ferree-Rand B & L Semi-Automatic Recording Perimeter, thesedevices require that an operator slowly manually move the visualstimulus over the patients visual field. Furthermore, these devices aredifficult to use; require a moderate-to-high degree of operator trainingin the use of thetester; are relatively expensive; and producerelatively poor correspondence between the test spots location and itsfinal recorded position in the patients visual field.

Among the performance criteria for such a vision tester are: adequatesensitivity to changes in visual performance that accompany the variousstresses encountered in space flight; sufficient comprehensiveness todetect the possibility of changes in visual functions other than thoseexpected; and adequate diagnostic value-the tester should not onlydetect a dysfunction, but should provide an indication of the extent ofits development.

SUMMARY OF THE PRESENT INVENTION It is therefore an object of thepresent invention to provide a convenient and practical means forautomatically measuring the visual sensitivity of the patients eyes, andfor accurately delineating the size and shape of the blind spots of thepatients eyes.

In accordance with the present invention, an automated visualexamination apparatus is provided which includes a movie projector forpresenting dynamic visual stimuli, an infinity collimating lens, a headpositioning support, a response button, an electronic control unit, anda two-pen XYY' response plotter. In the preferred embodiment, aIO-arc-minute diameter dim white spot of light is made to travel acrossa viewing screen along each of 12 meridians which are separated by 30arcs in the patients frontal plane and to randomly disappear andreappear during its traverse. The patient is instructed to press theresponse button each time the spot disappears, and to release the buttonwhen the spot reappears so that his responses can be recorded by one ofthe two pens of the plotter. The second pen records the on-off statusand movements of the visual stimulus. Various dysfunctions can then beassessed by comparing the plotted stimulus and response traces.

The present invention is sensitive to the presence of such dysfunctionsas scotomata, glaucoma, and changes in retinal sensitivity which are ofsuch magnitude as to make the dynamic visual stimuli invisible, and canbe used to perform other visual examinations by the preparation of otherstimulus films, such as glare recovery (using a strobe flash tubeaddition), motion perception thresholds, visual tracking ability (usingan eye tracking monitor addition), visual acuity (using an appropriatestimulus pattern on the film), critical fusion frequency measurements,and color perceptibility.

Among the advantages of the present invention are that all experimentalrandomizations, light level controls, and other necessary and criticalvisual characteristics of the stimulus are automatically controlled; useof the device does not require or involve any verbal pa tient responses;all electronic components are responsive to the stimulus display andpatient response button; use of specially prepared test films makes itpossible to randomize the presentation order of the visual stimuli; andthe device makes it possible to easily and accurately locate andstabilize the patients head and eyes during the testing period.

In addition to the space travel applications, an automated visualsensitivity tester having the characteristics described above would alsohave valuable clinical application in ophthalmological and optometricpractice due to its ease of operation, high reliability, and completelyautomated nature.

IN THE DRAWINGS FIG. 1 is a schematic diagram illustrating the basicoperative functions of a preferred embodiment of the present invention.

FIG. 2 is a diagram further illustrating the stimulus display screen ofFIG. 1.

FIG. 3 schematically illustrates an alternative embodiment of thepresent invention.

FIG. 4 illustrates an automated visual sensitivity testing system inaccordance with the present invention.

FIG. 4a further illustrates the X-Y coordinate selector shown in FIG. 4.

FIG. 5 illustrates the results of a visual sensitivity test for a normaleye using the apparatus of the present in'-' vention.

FIG. 6 illustrates the results of a blind spot mapping of a normal eyeusing apparatus in accordance with the present invention.

FIG. 7 illustrates the results of a visual sensitivity test for aglaucomatous eye using the apparatus of the present invention.

FIG. 8 illustrates the results of a blind spot mapping of a glaucomatouseye using apparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1of the drawings which is a schematic illustration (from the top) of avisual sensitivity tester in accordance with the present invention, itwill be noted that the apparatus includes a projection system 10 havinga suitable housing (not shown), a signal conditioning unit 12 jointlyresponsive to stimulus signals generated by projection system 10 andresponse signals input by a patient via the response switch 14, acontrol unit 16, and a multiple pen X-Y recorder 18.

Projection system 10 is comprised of a vertically mounted panel 20having a circular aperture 21 in its midportion to which asemi-transparent, semi-diffuse display screen 22 is affixed. Inaddition, a pair of photocells 24 are disposed in each of the upper andlower corners of panel 20 outside the bounds of screen 22. Affixed tothe front side of panel 20 is a shroud 26 for shielding that side ofscreen 22 from external light. Shroud 26 also serves as a support for aviewing lens 28 and filter unit 29 through which an eye 27 under testviews screen 22. A mirror 30 and three visual fixation cross projectors32, 34, and 36 are disposed opposite the rear side of panel 20. Thefixation projectors may either be positioned above and behind mirror 30,as indicated, or may be suitably positioned on the front side of mirror30 with their'light beams being reflected by mirror 30 onto screen 22. Amotion picture projector 40 including a light source 42, condensing lens44 and projection lens 46 is also provided for projecting images from amovie filmstrip 48 onto the rear side of panel 20 via reflection frommirror 30.

In accordance with the present invention, the image projected fromfilmstrip 48 includes a stimulus image, in the form of a moving whitespot of light, and a plurality of small coded spots of light disposed atfixed positions outside of the field falling on screen 22. The movingwhite spot is caused to sequentially move in a predetermined manner over12 meridians lying within that portion of the image which is projectedonto screen 22, while the coded spots of light are projected outside ofscreen 22 to fall on the photocells 24. The coded light spots causephotocells 24 to generate binary coded decimal signals corresponding tothe stimulus images meridian location, direction along each meridian,and on-off status.

In operation, the patient is instructed to fix his gaze upon a fixationcross at, for example, the point 50 (as screen 22 by projector 40 and iscaused to move first along one meridian and then another toward, or awayfrom, fixation cross 50. During the time that the spot generating beam54 (FIG. 1) is swung over the angle a (causing spot 52 to sweep over asingle meridian), it will be caused to momentarily disappear duringrandom portions of its sweep transverse. As spot 52 is swept slowly overeach of the 12 meridians, spot presence and location data in the form ofbinary pulses are generated by photocells 24, and this data is input tosignal conditioner 12. Switch 14 supplies the patient response inputsignals to signal conditioner 12. The conditioned signals developed byconditioner 12 are then fed into control unit 16 which in turn developsappropriate control signals for energizing the ink pens of recorder 18so that both the white spot path and the response thereto are recordedfor evaluation.

As an alternative to the motion picture projecting embodiment of FIG. 1,it will be appreciated that a cathode ray tube 60 can likewise be usedto generate similar dynamic test images similar to those projected inthe previous embodiment. In this embodiment, a program source 62, suchas a digital computer, a video tape player, a punched paper tape player,or some other suitable source of stimulus signals, is provided forconverting a prerecorded test program into input signals suitable fordriving the CRT control electronics 64 which, in turn, cause CRT 60 todevelop the desired test display. The program source 62 functions toreplace the conditioned photocell signals from signal conditioner 12.The vertical (Y) and horizontal (X) in- 'puts of the CRT controlelectronics 64 are connected in parallel with the X-Y recorder inputs.This results in the simultaneous X-Y control of the CRT dot and the pensof the X-Y recorder. The CRT dot and pens move in synchronism to providethe test image and record the results, respectively.

In FIG. 4 of the drawings, there is shown a more detailed preferredembodiment of an automated visual sensitivity tester in accordance withthe present invention which includes a rear projection, cartridgeloaded, super 8mm movie projection unit 110, a control unit 112, and aresponse plotter 114. Projection unit includes a display panel 1 16having a transparent, semidiffuse projection screen 118 and eightphotocells 120 mounted two in each corner as schematically illustratedin FIG. 1. Beneath display panel 116 and to the right side of theinstrument cabinet 121, a film cartridge insertion slot 122 is locatedfor receiving a film cartridge or cassette 124.

At the front of the cabinet beneath slot 122, a slanted control panel126 is provided which includes an ON lever 128 for turning the projectorON, an OFF button 130 for turning the projector OFF, a visual fixationprojector control toggle 132 which allows the visual fixation projectorsto beturned ON independently of the projector, a visual fixation crossselector knob 134 which is a three-positioned switch for individuallyturning on each of three visual fixation projectors, a cable plug 136for connecting the hand-held response switch 138 to the apparatus, animage focus knob 140, and a movie projector framing control knob 142 foradjusting the stimulus vertical screen position. Directly beneathcontrol panel 126 four shelves 144 are provided for storing extra filmcartridges.

An aluminum mask, or shroud 146 is mounted over display panel 116 on thepatients side of screen 118.

Although shroud 146 extends outside the locus of photocells 24, theviewing lens 28 limits the field of view to a 60 arc-diameter includingscreen 118. The eight photocells 120, which may for example, be of theClairex type CL-905-L are located outside of this field of view on thepatients side of panel 116. Mounted rigidly to the front of shroud 146is a viewing lens and filter mount 148 through which the patient 150views screen 118. In order to insure that the patients head is properlycentered behind the viewing aperture (lens) 152, an adjustable dentalimpression bite board 154 and adjustable forehead rest 156 are provided.However, as an alternative, a chin rest and a curved padded support atthe temples could also be used.

Within cabinet 121 are included film projecting components such as thelamp 160, condensing lens (not shown), projecting lens 162, asmall-sized reflector 164, a medium-sized reflector 166, a large-sizedreflector 168, and suitable film drive apparatus (not shown). Note thatwhen cassette 124 is included in the projector, the small reflector 164is positioned behind film 170 for reflecting the light passing throughfilm 170 up to projection lens 162. The projector is capable ofprojecting images from both color and bIack-and-white movie filmstripsonto screen 118. Since the film 170 contained within cassette 124 is acontinuous loop, no threading is required and the film can be stoppedand the cartridge removed from the tester at any time. Three visualfixation cross projectors 172 are also provided within cabinet 121 andare mounted in such a position that they will project into mirror 168.Projectors 172 project red crosses of minute-arc bar length upon viewingscreen 118, at its middle and about arc to the left and right of themiddle cross, respectively. The projectors 172 may, for example, includea 6.3 volt lamp, opal glass diffuser, photographic negative of a cross,focusable achromatic lens, and a red No. 24 Wratten filter. Lampluminance is controlled by adjustable resistors (not shown).

Projection unit 110 also includes signal conditioning circuitry (notshown) which converts the output of photocells 120 into binary signalsincluding: four binary coded bits denoting one of 12 preset stimulusmeridians; two binary coded bits denoting stimulus direction of travel(IN or OUT along a given meridian) and a HOLD or RESET command; onebinary coded bit denoting stimulus condition (light ON or OFF); and async bit which indicates whether the lamp 160 is ON or OFF. In additionto the photocell input, the patients response signals are also input tothe signal conditioning circuitry.

The conditioned signals are then fed into the programming circuitry 180of control unit 112 which includes a relay interface 182, a decodematrix 184, and a number of reed relays 186. Relay interface 182develops a stimulus signal on line 188, a patient response signal online 190, and binary coded control information which is coupled into thedecode matrix 184 on line 192. The decode matrix unit 184 develops OUT,IN, HOLD, and RESET signals on the lines 194, 196, 198, and 200,respectively, as well as actuating signals for the reed relays 186.Lines 194 and 196 out of decode matrix 184 are coupled into the OUT andIN terminals, respectively, of a voltage regulator 202 of the outputcircuitry 204 which, in addition, includes an integrator 206, bufferamplifiers 108 and 210, and an X-Y coordinate selection unit 212. TheHOLD and RESET signals on lines 198 and 200, respectively, are coupledinto integrator 206 and the decoded stimulus information is used todrive relays 186 which perform a channel selection function for X-Ycoordinate selection unit 212. Unit 212 develops an X-axis output online 214 and a Y-axis output on line 216 which respectively energize theX- and Y-axis drive units of plotter 114.

More specifically, the binary coded stimulus information is decoded bymatrix 184 and used to drive reed relays 186 to control an analogvoltage for input to unit 212. The stimulus direction of travel (IN orOUT) signals allow a plus or minus regulated voltage from regulator 202to drive the output of integrator 206 toward a first voltage (+5 volts)or back to a second voltage (0 volts). If the first command is OUT, theoutput of integrator 206 will initially move toward +5 volts. Thiscommand will then be followed by a HOLD command and then by an INcommand. The ramp output voltage will then move toward 0 volts. If thesequence is reversed (an IN command followed by a HOLD, followed by anOUT command), the output of integrator 206 will move from 0 volts toward5 volts followed by a HOLD condition then back toward 0 volts. Theresult of using both of these sequences is to provide 24 unique radialpen excursions, along the 12 preprogrammed meridians.

The ramp output voltage developed by integrator 206 on line 207 isbuffered by the two amplifiers 208 and 210 to develop plus and minusramp voltages on lines 209 and 211. The plus and minus ramp voltages arefed into X-Y coordinate selector 212 which, as better illustrated inFIG. 4a, includes two potentiometers 213 per meridian that are used topreset each of the X and Y coordinates of pen travel. Toggle switches215 are used to select the sign of the sine or consine functions forlocating the meridian within any of the four projection screen 118quadrants. For example, if the pens of response plotter 114 are supposedto move along the 30 meridian (all meridians are measured from the 12oclock position in the clockwise direction) the X-channel potentiometeris set for +0.866 and the Y potentiometer for +0.500. These valuesrepresent the cosine and sine of 30, respectively. An OUT command willthen cause the pens to move out from the center of the data recordingsheet along the 30 meridian. If, however, an IN command is initiatedfirst, the pen will travel along a 210 meridian (i.e., 180 from the 30meridian). Although the response plotters pens are driven in parallel,the patients response switch 138 and the stimulus OFF/ON informationcause the pens to drop onto the paper independently.

In operation, an eye positioning plate (not shown) is inserted into aslot just behind the viewing lens 152, and the visual fixation crossselector knob 134 is turned to the top left position,'if the blind spotof the right eye is to be tested; to the middle position, if the visualsensitivity of either eye is to be tested; and to the top rightposition, if the blind spot of the left eye is to be tested. The patientis then instructed to bite onto bite board 154 (or place his chin into achin rest) and to loosen the horizontal and vertical adjustment knobs155. He then slides bite board 154 horizontally and vertically until thefixation cross is seen through a small hole in.

the eye positioning plate, whereupon he tightens the adjustment knobsfinger tight and then adjusts the forehead rest 156. The eye positioningplate is then removed, and the test film is turned on to begin the test.

The patient is then told to hold the response switch 138 in hispreferred hand, resting his thumb on the but ton, and to maintain hisgaze directly upon the red cross and note the small white spot of lightwhich will travel slowly across the field of view in various direc='tions, and which will, from time to time, disappear. It is also pointedout that to make these visual tests valid, it is important that visualfixation (i.e., direction of gaze) be maintained on the small fixationcross projector on the screen throughout the test. The patient is tomerely press his finger button as soon as the white light disappears andto release the finger button the instant the white light reappears.

In accordance with one visual sensitivity testing scheme, the spottraverses radially outwardly or inwardly from the screen center point tomake interrupted traces such as those illustrated in FIG. 2 (see alsoFIGS. 5 and 7). The outer portions of the program film 170simultaneously project the coded light spots onto the several photocells120 which generate signals that, when fed into control unit 112, actuatethe stimulus recording pen of plotter 114. If the patient sees the spotdisappear and properly. depresses the button of switch 138, patientsresponse signals will also be generated for actuating the second pen ofplotter l 14 so as to inscribe a parallel mark (shown dashed in FIGS. 5and 7) next to the stimulus marks. However, when the patient sees thespot reappear on screen 118, he will, of course, release the controlbutton. The correspondence between the two parallel marks on the plotwill indicate his visual deficiency.

The visual sensitivity of a patient having a glaucomatous dysfunction isillustrated in FIG. 7 of the drawings which indicates a large scotoma inthe upper right-hand visual field along 30, 60, and 90 meridians fromthe foveal boundary out to a 30 arc radius limit. This may be comparedwith the test results of a patient having normal visual sensitivity andreaction times to the disappearance and reappearance of the moving whitespot of light as shown in FIG. 5.

In administering the blind spot mapping test (see FIGS. 6 and 8), thepatient is told to position his head as before, to fix his gaze upon thesmall cross on the screen, and to press the finger button whenever themoving white spot disappears and release the finger button when the spotreappears. In this case, however, the moving white spot of light isnever turned off as it traverses the patients field of view. Itdisappears only when its image falls upon the blind spot or other areasof retinal insensitivity. By using one of the visual fixation crosseslocated to one side of the center of the viewing screen and by causingthe moving white spot to traverse along each of the 12 meridianscentered upon the viewing screen (where the blind spot is also imaged),the image of the'white spot of light will traverse the blind spotsboundary. This produces a polar coordinate graphic plot of the boundaryof his blind spot. Because the white spot of light moves both OUT and INalong each meridian (thereby plotting the blind spot boundary from eachdirection in 12 locations), an experimenter makes a small vertical markwhenthe response plotters pen indicates that the patient has pressed hisresponse button for the IN direction of travel. The actual blind spotboundary is taken as the average of the OUT and the IN pen marks. InFIG. 6,

test results for a normal right eye are illustrated, while in FIG. 8 theresults are shown for an individual (the same patient as in FIG. 7)having a glaucomatous dysfunction.

Since the recorded data provided by the present invention is in the formof stimulus traces and associated response traces, it will beappreciated that the test resultsneed not necessarily be recorded inpolar coordinate form, but could likewise be recorded in strip chartform, or the like, where a switch means of reference is provided. Forexample, if in the case of visual sensitivity examination, the pentraces are made by fixed position pens which record on a moving strip ofpaper and some type of marker is provided to indicate which traces areincluded in each stimuli meridian and their respective radial positionsin a given meridian or other portion of a focal field, the data would bejust as interpretable as in the illustrated polar type of graph.

From these examples, the utility of the present invention will bereadily appreciated by those skilled in the art and certainmodifications and improvements thereof will no doubt become apparent. Itis therefore to be understood that the above disclosure is by way ofillustration only and is not intended to be limiting. Accordingly, theappended claims are intended to cover all such modifications andimprovements as fall within the true spirit and scope of the invention.

What is claimed is:

1. .Visual examination apparatus, comprising:

light receiving means including, a display screen for displaying visualstimuli to a patient, and photosensitive means responsive to light andoperative to generate binary coded decimal signals which control themeridian location and direction of the stimulous image;

light projecting means for projecting stimulus images onto said signaldisplay screen, and for projecting control images commensurate with saidstimulus images onto said photosensitive means;

said light projecting means including means for projecting light througha filmstrip containing said stimulus images and said control images andonto said light receiving means;

patient response means for developing response signals commensurate withsaid visual stimuli as perceived by said patient;

means responsive to said stimuli signals and said response signals andoperative to develop recorder control signals; and

a recorder responsive to said recorder control signals and operative toprovide a comparable record of said visual stimuli and the patientresponse corresponding thereto.

2. Visual examination apparatus as recited in claim 1 and furthercomprising means for projecting one or more fixed position fixationimages onto said display screen.

3. Visual examination apparatus as recited in claim 1 wherein said meansresponsive to said signals includes electronic control circuitryresponsive to said stimuli signals and said response signals andoperative to develop a first. set of said recorder control signals, saidcontrol circuitry being further responsive to said stimuli signals todevelop a second set of said recorder control signals.

4. Visual examination apparatus as recited in claim 3 wherein saidrecorder includes a pair of trace developing means responsive to saidfirst set of control signals, and positioning means responsive to saidsecond setof control signals and operative to position said tracedeveloping means.

5. Visual examination apparatus as recited in claim 1 wherein said lightprojecting means includes a cath ode ray tube and programmable means fordriving said cathode ray tube in accordance with a test program.

1. Visual examination apparatus, comprising: light receiving meansincluding, a display screen for displaying visual stimuli to a patient,and photosensitive means responsive to light and operative to generatebinary coded decimal signals which control the meridian location anddirection of the stimulous image; light projecting means for projectingstimulus images onto said signal display screen, and for projectingcontrol images commensurate with said stimulus images onto saidphotosensitive means; said light projecting means including means forprojecting light through a filmstrip containing said stimulus images andsaid control images and onto said light receiving means; patientresponSe means for developing response signals commensurate with saidvisual stimuli as perceived by said patient; means responsive to saidstimuli signals and said response signals and operative to developrecorder control signals; and a recorder responsive to said recordercontrol signals and operative to provide a comparable record of saidvisual stimuli and the patient response corresponding thereto.
 2. Visualexamination apparatus as recited in claim 1 and further comprising meansfor projecting one or more fixed position fixation images onto saiddisplay screen.
 3. Visual examination apparatus as recited in claim 1wherein said means responsive to said signals includes electroniccontrol circuitry responsive to said stimuli signals and said responsesignals and operative to develop a first set of said recorder controlsignals, said control circuitry being further responsive to said stimulisignals to develop a second set of said recorder control signals. 4.Visual examination apparatus as recited in claim 3 wherein said recorderincludes a pair of trace developing means responsive to said first setof control signals, and positioning means responsive to said second setof control signals and operative to position said trace developingmeans.
 5. Visual examination apparatus as recited in claim 1 whereinsaid light projecting means includes a cathode ray tube and programmablemeans for driving said cathode ray tube in accordance with a testprogram.